Help needed

Hello,
I have a closet in my grow room which is a second room in my apartment. It has a bifold door on it now.
The problem is ventilation. I rent so I don't want to destroy the bifold door by cutting a hole in it or something or cut any holes in any walls. I want to close in this closet so I can hold in heat inside the closet while main grow room remains cooler(I grow lettuce in main room which likes it cooler). I already have a grow tent in the grow room too which works great. I just want to utilize this closet that I have too if I can do so inexpensively.

I need some way to close in the closet and be able to somehow put it in line duct fan hole in. However I'm not good at carpentry or building things, and wonder if anybody has any suggestions on closing in this closet and being able to add ventilation? Trying to do it cheaply, and within my skill set. I could give to shits about aesthetic value personally, just need it to function.

Panda film.

Or blackout curtain with duct
Or a sheet of plasterboard
Or ply

Hi thanks for all of the suggestions.
This morning I stumbled upon this in my research.


I think this is going to be perfect! Cheap, easy to install, can cut a hole in it easy enough hopefully. It's designed for dogs to bust through it so it should hold up for a while.

Not too shabby, 25$
Still got to cut a hole for some sort of ventilation solution.
Any suggestions are appreciated! not trying to buy another $100 AC Infinity in line if I can help it. Have one in my tent but I'm trying for a cheaper solution for this.